1.0 Technical Field
The invention relates to a profile member and, in particular, to a thin-walled profile member having localized material or structural anisotropisms.
2.0 Background of Related Art
It is known to use material or structural anisotropisms to produce global deformation couplings, for example, deformation couplings involving the whole cross-section of a profile, such as the tension-torsion or bending-torsion coupling.
Aerodynamically effective contours, such as wings, rotor blades, propeller blades, compressor and turbine blades or other means are constantly being aerodynamically optimized. But constantly changing loads, caused by unsteady and non-homogeneous flows and causing unsteady lift and resistance forces, also have to be considered. Flaps or slats may be used to control these forces in a known manner.
Where blades of helicopter rotors are used there is an unsteady airflow onto them. As the speed of flight increases so too does the complexity of the flow conditions. In the region at the tip of the blade compression impacts occur at the advancing blade at an angle "psgr" of approximately 90xc2x0, together with a sharp rise in resistance as a result of transonic flow, whereas at the retreating blade at an angle "psgr" of approximately 270xc2x0 and a maximum forward-flying speed unsteady shedding of vortices takes place, described as dynamic airflow break-away. The break-away causes a sudden collapse in the lift, giving rise to a temporary, very strong moment load which turns the rotor blade top-heavily around the rotor""s axis of rotation and produce s a structural-mechanical load.
There is therefore needed in the art a thin-walled profile with profile variation using material or structural anisotropisms, whereby a further increase in aerodynamic efficiency, a reduction in mechanical loads and a decrease in sound emissions are obtained.
One object of the invention is to provide a thin-walled profile with profile variation using material or structural anisotropisms, whereby an increase in aerodynamic efficiency, a reduction in mechanical loads, and a decrease in sound emissions are obtained.
In accordance with the present invention, a thin-wall profile is provided in which material or structural anisotropisms are arranged locally in the profile to produce specific changes in contour.